Snell's Law Problem (Please Help !)

A costume jewelry pendant made of cubic zirconia is submerged in oil. A light ray enters one face of the zirconia crystal, then travels at an angle of 25 degrees with respect to the normal. What was the ray's angle of incidence on the crystal?

Hi aliciadombros and welcome to PF. What is medium 1 and what is medium 2? It seems that if you are looking for the angle on the crystal and the unknown angle is θ1, then medium 1 must be oil and medium 2 must be zirconia. You used 2.18 for n1. Is the index of refraction for oil 2.18?

Your last solution is correct. I plugged in the numbers and the answer that I get agrees with yours, 39 degrees. How sure are you that the answer is 35 degrees? Sometimes posted answers or answers in the back of the book are incorrect.